Effect of sodium fluoride-induced toxicity on the renal cortex of lactating mice and their offspring: a light and electron microscopic study Fadia K. Abdo, Mohammed E. Khalifa, Rania A. Zidan and Sara M. Abdel Aal Department of Histology and Cell Biology, Faculty of Medicine, Zagazig University, Egypt Correspondence to Rania A. Zidan, Department of Histology and Cell Biology, Faculty of Medicine, Zagazig University, Egypt Tel: + 105005052; fax: + 050 6962700; e-mail: 59993@yahoo.com Received 20 March 2011 Accepted 26 April 2011 The Egyptian Journal of Histology 2011, 34:554–565 51 (1288 -2011) Introduction Fluoride is commonly added to drinking water for its clarification and to reduce tooth decay. However, fluoride was shown to have cumulative toxic effects on various organs, including the kidneys. Aim of the study To investigate the impact of sodium fluoride toxicity of drinking water on the histological structure of the renal cortex of lactating mice and their suckling offspring. Materials and methods Forty mice (20 mothers and 20 of their offspring) were used in this study and divided equally into four groups: group I (control mothers): allowed ad libitum access to tap water without any added sodium fluoride during pregnancy and lactation, group II (treated mothers): drinking tap water containing NaF (0.5 g/L) from day 15 of pregnancy until day 14 after parturition, group III: (suckling offspring of control mothers) and group IV: (suckling offspring of treated mothers). All mice were killed on postnatal day 14. Specimens were prepared for light microscope examination (hematoxylene and eosin and periodic acid-Schiff) and electron microscope examination. In addition, tubular epithelial height and tubular diameter were measured morphometrically and analyzed statistically. Results Examination of the renal cortex of treated mothers (group II) showed atrophic glomeruli with widened glomerular spaces. Tubules appeared dilated with decreased epithelial height as proved morphometrically. Tubular cells had a vacuolated cytoplasm and pyknotic nuclei. The apical brush border of many proximal tubules showed a weak and disrupted periodic acid-Schiff reaction. Ultrastructurally, some proximal lining cells showed heterochromatic nuclei, numerous cytoplasmic vacuolation of variable sizes and small scattered rounded mitochondria associated with loss of basal infoldings. However, the distal tubules maintained their basal infoldings and organized mitochondria. Podocyte foot processes were distorted and rested on a thickened glomerular basement membrane. The suckling offspring of the treated mothers showed less severe tubular injury than observed in their mothers as the tubular dilatation and the epithelial height were not affected significantly. Conclusion Sodium fluoride induced various degrees of damage to the structure of renal cortex. The lactating mice renal cortices were severely affected compared to those of their suckling offspring. Thus, it is recommended to adjust the fluoride content in the municipal water supply and to avoid excess fluoride intake especially for lactating mothers. Keywords: fluoride, lactating mice, renal cortex, suckling offspring Egypt J Histol 34:554–565  c 2011 The Egyptian Journal of Histology 1110-0559 Introduction Fluoride is an essential electronegative element that has protective effects against bone mineral loss and dental caries [1]. The main source of fluoride is tap water as it is commonly added to the municipal water supply of many countries for the purpose of clarification [2]. Other sources of fluoride include food, processed beverages, and drugs. Foods rich in fluoride include fish, nuts, and dark green vegetables, which accumulate fluoride from soil and water [3]. Dental gels, tooth pastes, and mouth rinses mainly contain fluoride [4]. Consumption of 1 mg fluoride per day is essential for humans as fluoride is safe and effective when consumed properly [5]. 554 Original article 1110-0559  c 2011 The Egyptian Journal of Histology DOI: 10.1097/01.EHX.0000399972.96108.38 Copyright © The Egyptian Journal of Histology. Unauthorized reproduction of this article is prohibited.